The nature of the restriction in the specificity of antibody production in the pig towards lysozyme as contrasted to goats and rabbits is being studied. F(ab) fragments from pig, goat, and rabbit antilysozyme antibodies either through papain or pepsin digestion followed by reduction will be prepared. The number of F(ab) fragments bound to lysozyme molecule will be determined. Also the specificity of the binding of the F(ab) fragment to one of the three immunochemically reactive fragments of lysozyme will be ascertained.